The source/drain contacts of a carbon nano-tube/graphene device are Schottky contacts, which introduces two major challenges to the device fabrication. The first challenge is how to make a self-aligned metal source/drain process to minimize gate underlap so as to enhance gate control to the source/drain Schottky junctions. The other challenge is how to reduce contact resistance of the Schottky contact between the source/drain metal to the carbon nano-tube or graphene. Metal with the right work function is the key for the contact resistance. With conventional fabrication schemes, for example, one metal (typically palladium (Pd)) is used for p-channel field-effect transistors (PFETs) and another metal (for example aluminum (Al)) is used for n-channel field-effect transistors (NFETs). The conventional fabrication process is not self-aligned. The use of multiple metals in a given fabrication scheme, however, increases production complexity, time and thus overall costs.
Thus, techniques for fabricating carbon nano-tube/graphene devices that efficiently and effectively meet the above-stated challenges would be desirable.